This invention relates generally to valves, and more particularly concerns a valve of the type described in U.S. Pat. No. 3,938,553 and in which a drain passage of highly unusual construction and function is incorporated.
There are times when valves as shown in the above mentioned patent are connected with solar panels or heating equipment for heating liquid such as water flowing to a pool or other water body. It is desired that water in the solar heating equipment be drained when the equipment is not in use, as otherwise such water in the equipment might boil in the daytime, or freeze at night. While an additional drain valve may be employed to drain the solar heating equipment, the user may forget to open that valve to drain position when necessary; also the drain valve represents added costs. Attempts to resolve this problem have included valve designs as in U.S. Pat. No. 4,169,491; however, the incorporation of drainage as shown in that patent necessitates a major re-design of the basic valve itself, which is costly and otherwise objectionable.